Electrolytic capacitor

Abstract

An electrolytic capacitor includes a capacitor element and an electrolytic solution. The capacitor element includes: an anode body including a dielectric layer; a cathode body; and a solid electrolyte in contact with the dielectric layer. The electrolytic solution includes a solvent, a solute, and a polymer component. The solvent includes an ethylene glycol compound. The polymer component includes polyalkylene glycol. The polyalkylene glycol includes at least one of (i) a mixture of polyoxyethylene and polyoxypropylene and (ii) an oxyethylene-oxypropylene copolymer. In the polyalkylene glycol, a molar ratio m/n of oxyethylene units to oxypropylene units is greater than 1.

What is claimed is: 
     
       1. An electrolytic capacitor comprising a capacitor element and an electrolytic solution, the capacitor element including: an anode body including a dielectric layer; a cathode body; and a solid electrolyte in contact with the dielectric layer, wherein:
 the electrolytic solution includes a solvent, a solute, and a polymer component, 
 the solvent includes an ethylene glycol compound, 
 the polymer component includes polyalkylene glycol, 
 the polyalkylene glycol includes an oxyethylene-oxypropylene copolymer, 
 a molar ratio m/n of oxyethylene units to oxypropylene units in the polyalkylene glycol is greater than 1 and less than or equal to 5, and 
 a number-average molecular weight of the oxyethylene-oxypropylene copolymer ranges from 1,000 to 5,000, inclusive. 
 
     
     
       2. The electrolytic capacitor according to  claim 1 , wherein a proportion of the ethylene glycol compound in the solvent is more than or equal to 10% by mass. 
     
     
       3. The electrolytic capacitor according to  claim 1 , wherein the ethylene glycol compound is at least one selected from a group consisting of ethylene glycol and polyethylene glycol, the polyethylene glycol including oxyethylene units at repeating number ranging from 2 to 8, inclusive. 
     
     
       4. The electrolytic capacitor according to  claim 1 , wherein a number-average molecular weight of the oxyethylene-oxypropylene copolymer ranges from 1,000 to 3,000, inclusive. 
     
     
       5. The electrolytic capacitor according to  claim 1 , wherein a concentration of the oxyethylene-oxypropylene copolymer in the electrolytic solution is less than or equal to 50% by mass. 
     
     
       6. The electrolytic capacitor according to  claim 5 , wherein a concentration of the oxyethylene-oxypropylene copolymer in the electrolytic solution is more than or equal to 5% by mass. 
     
     
       7. The electrolytic capacitor according to  claim 5 , wherein a concentration of the oxyethylene-oxypropylene copolymer in the electrolytic solution is more than or equal to 20% by mass. 
     
     
       8. The electrolytic capacitor according to  claim 1 , wherein the solute includes an acid component and a base component. 
     
     
       9. The electrolytic capacitor according to  claim 1 , wherein the electrolytic solution further includes at least one kind of ester compound selected from a group consisting of (i) a condensation product of a boric acid and a hydroxy compound and (ii) a condensation product of a phosphoric acid and a hydroxy compound.